Here is an Amazon link to the harness I started with.
Below is a wiring diagram for the 5 flat trailer harness that is part of the link above.
Next is the wiring diagram and a photo of the wiring harness the kit already comes with.
To start, take your Curt adapter harness which will be the Plug and Play portion of the harness and locate the connector that has five wires and a flat connecter.
Cut the blue and brown wires in this harness. (Note the wiring diagram above shows the blue as purple). Next I stripped the wires and slipped heat shrink tubing over the wires. I crimped the male ends on to the wires and then soldered them as well. You don't have to solder them but I always prefer to. After crimping and soldering the male ends on to the blue and brown wires, I slid the heat shrink up and heated it up to cover the soldered end.
Next I removed the unused wires and plug from the harness by removing the plastic loom that came on the harness and cutting them short near the connection points. I placed heat shrink over the ends and heated them up. The last thing I did to prepare the harness was slip some Alex Tech Expandable Sleeving over the wires and used electrical tape and heat shrink to secure the ends of the expandable sleeving over the wires.
Your plug and play harness is now built. Now onto the install.
Disconnect your connector that plugs into your trailer light plug behind the bumper on your truck. Plug the trucks wiring harness into one side of your new plug and play harness and the other side of your plug and play harness to the trailer lights connector on the back side of your bumper. Now take your Diode Dynamics Reverse Light Wiring Harness and plug the Yellow Wire from your Diode Harness into the Blue Wire of you plug and play harness. Plug the Blue Wire of your Diode harness into the Brown Wire of your Plug and play harness. (I know, I know it feels like Blue should connect to blue to me as well but I am working with two harnesses from two manufacturers so in this case Blue DOES NOT connect to blue. Sorry ladies and gentlemen.)
Now you can connect the plugs on your Diode Dynamics Reverse Light Harness to your Lights. Run the rest of the harness to the front of the truck. You have a few options at this point.
You can hook up the power and ground wires respectively from your Diode Dynamics harness and coil up the remaining wires and switch and be done. If you leave the switch in the center neutral position your lights will work automatically.
Option 2: You can do exactly as you did above but route the wires inside the truck and mount the switch at your desired location inside. This will give you the option to have the lights work automatically when the switch is in the neutral position, Turn on the white main beam by flipping the switch to one position or manually turn on the red back lights by flipping the switch the opposite position.
Option 3: You can ditch the switch with Diode Harness and wire in to the auxiliary/upfitter switches. There are already writeups and videos on that but if I need to update this with specifics, I will.
Let me know if I left anything out or if you have any specific questions. The harness isn't terribly hard to build and I hope this helps anyone that would like to save money and do it themselves. There are shortcuts and easier ways to build it but I don't work that way. If I am building something for you or me, I will take the time and do it the way I feel is best.
I will make several of these harnesses for people that wish to buy them from me. Full transparency they aren't that expensive to build but I have to charge for the time it takes me as well. My cost on the materials is close to but a little less than $40 per plug and play harness. That does not include the Diode Dynamics Harness. I will build a few more to come up with a price I feel is fair for my time and get them up on the site.
Thank you all for the support and I hope this helps some of you that want to do it on your own! It is my way of giving back when and where I can.